Arythmetic Relationship – where things change in direct proportion.  Also called straight line

Straight Line – if you plot a change in one thing it will directly change other things

Exponential Relationship (Geometric Progression) – is a rapid change that is not directly related

Platting Efficiency – the percent of cells that do survive the Petri dish

Cell Survival Curve – counts numbers of colonies that survive after varying doses of radiation

D37 – the dose required to reduce cellular survival to 37% of the initial cell population. (Note: Do becomes D37 only when the survival cirve is a simple exponential / forms a perfect straight line where the slope never changes)

D0 – The dose required to reduce cellular survival to e-1 = 0.37 on the linear portion of the dose survival curve. bring a certain log to 37% survival.  True radiosensitivity of a cell is measured by D0 (it is related to the slope of the curve)

Dq – (Quasithreshold Dose) – is a back exptrapolation which is defined as the dose derived from back extrapolation of the straight line portion of the curve where it intersects with 100% survival.  The dose requires to bring a cell to only 1 hit left

Single hit / single target – DNA was hit once and the cell dies

Multi hit / multi target – cells can have a different number of targets or have to be hit a different number of times (typically the same for same cell lines)

n – number of targets required to eliminate the cell (shoulder region /ELkind Repair

LET – linear energy transfer : is the energy deposited per unit track length in tissue

RBE – ratio of the absorbed dose of a standard type of radiation to that of the test radiation required to produce the same degree of stipulated biological effect

OER   :   OXYGEN ENHANCEMENT RATIO - The ratio of the reaction of cells to dose without oxygen versus with oxygen

Oxic – cells that are fully oxygenated

Hypoxic – cells that have a little oxygen

Anoxic – cells that have no oxygen (DEAD)

Oxygen -  is the best radiosensitizer we have for LOW LET radiation.  Is also know as the universal sensitizer / oxygen effect

“fixing” or “making permanent” the damage – terms used to to describe oxygens effect on free radicals where it helps them to stay as free radicals and will not recombine

Bi – Phasic Curve – the proportion of hypoxic cells to oxygenated cells increases in the way where the Initial Response to the dose of radiation is good because the outer layer is oxygenated but as those cells are killed and we peel back to the more hypoxic cells now these hypoxic cells respond differently than the onxygenated cells and will be killed more slowly therefore the slope is more shallow

Hypoxic Component of Tissue – can be back extrapolated from the point where the initial change from oxygenated to hypoxic cells takes place on the curve.  This point will back extraplolate to the percentage of cells that are hypoxic